Solar cells can be connected in series to form strings. When one or more solar cells in the string malfunction or are shaded from sunlight, the malfunctioning or shaded solar cells become highly resistive. As a result, other solar cells in the string may not generate enough voltage to overcome the resistive cells and thus current will cease to pass through the string. Bypass diodes can be connected in parallel with groups of solar cells (one or more solar cells connected in series) to allow current to bypass groups of solar cells having one or more highly resistive solar cell. In this way, current can continue to run through the string even when one or more solar cells malfunction or are shaded. However, large and efficient solar modules generate such large currents that when these large currents pass through the bypass diodes there are unwanted power losses and heat, and even bypass diode damage. Even low loss diodes (e.g., Schottky diodes) may not be able to overcome the losses, heat, and potential damage.
U.S. Pat. App. Pub. No. 2011/0068633, published on Mar. 24, 2011, discloses a protective circuit for a solar module. The protective circuit includes a trigger circuit and a switching arrangement, which in the case of shading of the solar cells is activated to provide a current bypass.